Israeli air strikes on the Gaza Strip killed five Palestinian fighters and a ground raid killed another one, Palestinian medics said early Wednesday. An Israeli army spokeswoman confirmed the air strikes, saying missiles were aimed at gunmen who had fired mortar bombs at Israeli forces operating in another part of the Gaza Strip. Another Palestinian was seriously wounded.

Earlier it was reported that Israeli troops launched a raid inside the Gaza Strip and clashed with Hamas security forces. Israel said the army moved into Gaza to destroy a tunnel built to capture Israeli soldiers.

It was the first reported armed clash between Israeli and Palestinian forces since a June 19 calm. "Qassam fighters are engaging in violent armed clashes with a Zionist (Israeli) force that raided east of central Gaza Strip," the Hamas statement said, according to Reuters. Locals in the area of the al-Bureij refugee camp in the central Gaza Strip reported seeing Israeli soldiers about 300 metres inside Gaza Strip.

They also reported hearing shots fired from Israeli military vehicles positioned on the Israeli side of the border fence and the buzz of unmanned drones overhead. According to the residents, Hamas gunmen had responded by firing at the troops. Residents said that one of the Israeli drones fired a missile into the area where the firing had occurred.

On his part, Hamas spokesman Sami Abu Zuhri said the raid proved that Israel was not interested in continuing the calm. "The aggression is a major violation of the agreement. If such raids are repeated, fighting will not be limited only to the area east of the central Gaza Strip," Abu Zuhri said.

A statement from Hamas' armed wing said "the current calm agreement will not prevent us from defending our people against Zionist (Israeli) arrogance". It warned of a harsh response.